1. Field of the Invention
The present invention relates to a multiple input multiple output (MIMO) wireless communication system. More particularly, the present invention relates to a transmission method and a MIMO wireless communication system using the same.
2. Description of Related Art
A MIMO wireless communication system is a wireless communication system with multiple antennae, and the multiple antennae at a transmitting terminal of the wireless communication system can independently transmit signals, and meanwhile a receiving terminal thereof can receive and obtain original information transmitted by the transmitting terminal through the multiple antennae. Since in the MIMO wireless communication system, dada throughput and a transmitting distance of the system can be greatly increased without increasing a bandwidth or a total transmitting power loss, the MIMO wireless communication technique is popular in recent years.
A core concept of the MIMO wireless communication system is to effectively improve a spectrum efficiency of the wireless communication system based on spatial freedoms provided by a plurality of transmitting antennae and a plurality of receiving antennae, so as to improve a transmitting rate and a communication quality. Referring to FIG. 1A and FIG. 1B, FIG. 1A is a system block diagram illustrating a conventional MIMO wireless communication system, and FIG. 1B is a constellation diagram of signals within the MIMO wireless communication system of FIG. 1A. The conventional MIMO wireless communication system 10 includes a transmitting terminal TX_10 and a receiving terminal RX_10, wherein the transmitting terminal TX_10 includes a signal processing unit 101 and transmitting antennae A1-A3, and the receiving terminal RX_10 includes receiving antennae B1-B3, a signal processing unit 102, and decision units DEC_1-DEC_3.
The transmitting terminal TX_10 receives a bit sequence CData and divides the bit sequence CData into three bit sub-sequences D1, D2 and D3. The signal processing unit 101 receives the bit sub-sequences D1-D3 and respectively processes the bit sub-sequences D1-D3, and then transmits the processed results to a wireless transmission channel through the transmitting antennae A1-A3. The receiving antennae B1-B3 of the receiving terminal RX_10 receive the signals from the wireless transmission channel, and then the signal processing unit 102 processes the signals received by the receiving antennae B1-B3. Thereafter, the decision units DEC_1-DEC_3 respectively decide contents of bit sub-sequences D1′-D3′ according to the processed signals C1-C3. Finally, the receiving terminal RX_10 can assemble the bit sub-sequences D1′-D3′ into a bit sequence CData′.
Generally, if a channel impulse response of the wireless transmission channel can be correctly pre-estimated, and in case that the channels are mutually independent, and if a noise influence thereof is not great, the bit sequence CData′ is equivalent to the bit sequence CData, theoretically. In this example, the signal processing unit 101 can modulate the bit sub-sequences D1-D3, and a modulation method thereof is quadrature phase shift keying (QPSK). The constellation diagram of the signals transmitted by the transmitting antennae A1-A3 is as that shown in FIG. 1B. The signals received by the receiving antennae B1-B3 are combinations of the signals transmitted by the antennae A1-A3, and in the wireless transmission channel, the noises are inevitably superposed to the transmitted signals, so that dots on the constellation diagram (FIG. 1B) of the signals received by the receiving antennae B1-B3 may have a scattered distribution. Therefore, the signal processing unit 102 has to be applied to process the signals received by the receiving antennae B1-B3, so as to generate the signals C1-C3. In case of an ideal circumstance, a dot distribution of the constellation diagram (FIG. 1B) of the signals C1-C3 is the same as that of the signals transmitted by the transmitting antennae A1-A3.